Agitation during development.

For developing tri-x, Kodak recommends 5-7 initial inversion cycles in 5 seconds, then 5-7 inversions every 30 seconds. That's what Kodak says for N development. At the darkroom I'm involved with, everyone seems to have their own style, but most agitate for 30 seconds initially, then 10 seconds every minute after that. It would seem this would give you different negatives than if following Kodaks recommendations. It's 2-3x more agitation that they recommend. Does it really matter how you agitate, so long as it's consistent?

Either method produces good negatives. If you are more comfortable with Kodak's instructions then by all means follow them.

The one thing I learn from following Apug is that consistency is king. Only if you are consistent can you fix problems reliably and quickly. So like Gerald says, either is good, and I've used both in the past.

PS: "different" does not equal "bad" especially in darkroom work. As long as you're consistent you can experiment with the difference between different differents and pick the one that makes the best prints for you

Yes it does affect how the negative turns out. More agitation pushes your highlight higher. Less, pulls your lightlights down.



The normal agitition method is first minute then 2 inversions every 30 sec.

Less agitation method is first minute then 2 inversion every minute.

^ Both of these methods are that I use depending on the rolls contrast. ^



So if you have a low contrast scene you would want to agitate more so you can push the highlights a little higher for more contrast.

But if you have a high contrast scene, you would want to agitate less to retain the highlights and less contrast.

It is because the developer for the highlights exhausts locally faster. So if you let it sit longer in-between inversions the highlight will not develop as much and will lower the contrast of film. (agitation does not affect shadows, within reason)

The opposite is also true. If you agitate more often, you will be giving the highlights new developer and it will develop more increasing the contrast.

For D-76 1:1, small tank, I definitely do agitation on 30-second intervals during development.

I will say that when I do it this way, for 35mm, I can measure differences between frames at the center of the reel versus the middle and the outside.

Stand development, if that's what you want to do... is a different story altogether.

I'm not sure what developer you're using, but w/ D76 and most other developers (except Rodinal) I use 30 seconds of gentle swirly inversions, 2 gentle swirly inversions every 30 seconds, and none the last minute. Comes out perfect.

Does it really matter how you agitate, so long as it's consistent?

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Unless your agitation method is causing problems (streaking, uneven development, etc) then no, it does not really matter how you agitate the KEY thing is to be consistent. As you have seen from the previous replies, everyone has their own way of working. In my case, what works for me is:

• All chemicals always at 20˚C
• Two minute pre-soak.
• All stages up to the washing of the film with the same agitation method: four gentle inversions over the first 30 seconds followed by one gentle inversion every following 30 seconds.
• Washing is different as I use a variation of the Ilford washing method that involves constant inversions.

Whether the Stop Bath and Fixer require the same agitation is a matter of opinion that tends be as different as every photographer on APUG, I simply use the same agitation because then I don't have to think about it as every bath (I use a two-bath developer) receives the same agitation sequence.

So back to your question again, consistency and repeatability (rather than how you do something) are paramount. Once you consistently use a repeatable processing sequence you then can easily assess any given changes that you might want to make (such as reducing development time if your negatives are consistently too contrasty or increasing development time if your negatives have too little contrast) to adjust how your negatives come out and how easy they are to print how you want them.

Best of luck finding what works for you.

David.
www.dsallen.de

cjbecker said:

Yes it does affect how the negative turns out. More agitation pushes your highlight higher. Less, pulls your lightlights down.

...

So if you have a low contrast scene you would want to agitate more so you can push the highlights a little higher for more contrast.

But if you have a high contrast scene, you would want to agitate less to retain the highlights and less contrast.

It is because the developer for the highlights exhausts locally faster. So if you let it sit longer in-between inversions the highlight will not develop as much and will lower the contrast of film. (agitation does not affect shadows, within reason)

The opposite is also true. If you agitate more often, you will be giving the highlights new developer and it will develop more increasing the contrast.

Click to expand...

While this is true, most of us prefer to alter developing time and not agitation to achieve differences in contrast index. Varying time and keeping all other things constant is more predictable and repeatable.

There are times when one wants a minimal agitation scheme, e.g., stand or semi-stand agitation, for a particular purpose; some use reduced agitation schemes exclusively. Even in this case, contrast control is usually accomplished by changes in developing time.

I would recommend to the OP that agitation be kept constant. I like the scheme with an initial 30 seconds of agitation followed by 10 seconds every minute as long as the negatives do not exhibit any streaking, mottling, etc. If that were the case, I'd agitate 30 seconds to start and then 5 seconds every 30 seconds thereafter.

Best,

Doremus

Cjbecker gave you a good hint: agitation affects contrast of your negative. More agitation means more contrast, and less means less contrast—as long as you do not reduce agitation so much that you begin using semi-stand, or stand development, which are useful, but quite specialised, rather than general-use techniques, and as such they bring a whole raft of their own issues to deal with.

Similarly, you can influence the contrast by changing the duration of negative development: longer development means more contrast, less development means less contrast. In fact, changing the duration of development is the most common method of controlling the contrast of your negatives, whilst keeping agitation always the same. It is easier to predict continuous changes to contrast levels from development duration changes, than from somewhat discrete changes to agitation patterns. Zone System, BTZS, and many other time-tested approaches to negative contrast control, and the foundation of sensitometry (curves), and, of course, manufacturer recommendations by Kodak and Ilford, or equipment manufacturers like Jobo, advocate keeping agitation consistently same, and adjusting development time to achieve required changes to negative contrast.

If in doubt, do what the manufacturer has recommended. They want your images to succeed, because they realise that you are more likely to use their products if they gave you good recommendations that lead to repeatable, easy, error-free results.

PS. After I posted this, I noticed Doremus's post, with which I fully agree. Sorry for duplication...

Doremus and Rafal Lukawiecki

I fully agree and would also suggest the op to vary time instead of agitation to vary contrast. From the op question I kinda got into tunnel vision and never left it.

But knowing how agitation affect your outcome is a nice tool to have.

mporter012 said:

It would seem this would give you different negatives than if following Kodaks recommendations.

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Probably such a minor difference that it would be hard to discern.

My negatives that are BTZS tube developed, have more contrast than my tray developed negatives. When I tray develop, it's because I want more fully developed shadows and sharper negatives. I use minimal agitation, usually 10sec every 3 minutes, in staining developers (pyrocat-hd, or OA).

I wish that everyone on APUG would get a copy of Richard J Henry, Controls in Black-And-White Photography. He investigated many fervently held beliefs such as agitation in a controlled scientific manner. This book would decrease the number of questions that are asked again and again usually without any apparent resolution. IIRC, he found little difference between agitating for 10s every minute and 5s every 30s. But do get and read the book it is well worth the money.

Film development is a diffusion controlled reaction. The rate of development is the rate of diffusion of fresh developer into the emulsion. PLEASE EVERYONE READ THE NEXT SENTENCE CAREFULLY, PARTICULARY THE UNDERLINED WORD. The only thing that can change the rate of diffusion is temperature. Notice that I was careful to say rate of diffusion and NOT rate of development. The two things are not completely identical. Agitation insures that there is fresh developer on the surface of the emulsion. But its effect on the overall development rate is not as important as most people think. This is exactly what Dr Henry found empirically.

If I tuck the tank under my armpit and shuffle round the kitchen to the rhythm of La Cucaracha, I get particularly brilliant mid-tones

pdeeh said:

If I tuck the tank under my armpit and shuffle round the kitchen to the rhythm of La Cucaracha, I get particularly brilliant mid-tones

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I just pour the dev in set the timer and pour the dev out, after the timer goes of...
no pre soak, plain water rinse
then plain hypo fis
then rinse water
then 2 mins in hypo clear,
then Ilfords archival three rinses.

All the liquids are at the same temp within a degree C normally 20C, I don't bang tanks either never seen any air bubbles.

I use ID68 or Rodinal, sometime a Borax bath after Dev before rinse.

Noel

Thanks for all the replies!

mporter012 said:

For developing tri-x, Kodak recommends 5-7 initial inversion cycles in 5 seconds, then 5-7 inversions every 30 seconds. That's what Kodak says for N development. At the darkroom I'm involved with, everyone seems to have their own style, but most agitate for 30 seconds initially, then 10 seconds every minute after that. It would seem this would give you different negatives than if following Kodaks recommendations. It's 2-3x more agitation that they recommend. Does it really matter how you agitate, so long as it's consistent?

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hi there

all great responses, AND some required light reading

one thing that you might do is shoot a few rolls ... ( of the same film )
process some one way, process the others the other way
and see which way suits your style and printing process after that ...
i was always taught to agitate slow and deliberately like a figure 8 10 seconds every min after
agitating a full minute at the beginning of the operation ...
but thats me, and it sorta suits what i do afterwards ...
take notes, make a notebook, make mental notes .. and
then you know what you did and liked, so you can repeat it later ...
you might also consider bracketing your exposures and doing the whole operation
again ( and maybe again after that ) so you have a great idea what happens
when you over exp under e &c film too ...

we'll leave the light on when you have more qwestions

john

Gerald C Koch said:

I wish that everyone on APUG would get a copy of Richard J Henry, Controls in Black-And-White Photography. He investigated many fervently held beliefs such as agitation in a controlled scientific manner. This book would decrease the number of questions that are asked again and again usually without any apparent resolution. IIRC, he found little difference between agitating for 10s every minute and 5s every 30s. But do get and read the book it is well worth the money.

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My copy of Todd-Zakia Sensitometry explained the importance of agitation, and yes you want to deliver fresh developer to the laminar layer (thin layer of developer which is in contact with the film. Turbulent agitation is the key to making that happen. IIRC there's no help for the current thread, as the recommendation is 12 rocks a minute. That doesn't help those who do roll-film developing.

I also like to think in terms of working habits. Agitating every 30 seconds is a habit which keeps me paying attention to your film. In 30 seconds, I have about enough time to perform one minor task such as rinsing a beaker. But that's about all I can do. If I had a full minute break, I can assure you I would "forget" what I was doing. So a one-minute agitation regimen would possibly turn into two or three minutes on occasion. I know it does when I am fixing the film.

All chemical reactions are a matter of kinetics. One of the first things you learn when taking a course in chemical kinetics is that the overall rate of reaction is the rate of the slowest reaction. The development process consists of two steps, the diffusion of developing agents into the emulsion and the reduction of silver halide crystals by the developing agent. This can be given as where k represents a reaction rate constant.

A --> B k1 (diffusion)
B --> C k2 (development)
A --> C k = k1 (overall)

The first reaction is very slow while the second is very fast.

Now the diffusion rate is calculated from Fick's Laws. Of particular interest is the term (c1 - c2) which would describe the concentrations of developing agent in the developer solution and the emulsion. Now for the typical developer the change in concentration of developing agent c1 decreases by perhaps 5% during the entire development time. So each agitation to bring fresh developer to the emulsion surface does not have that great of an effect. The term (c1 - c2) remains nearly constant. The value of c1 just does not change that much. The point being is that agitation style is not that important a factor. Remember we are dealing with the slow reaction. People fixate on this point when whether you agitate every 30s or every 60s doesn't matter. Pick a method and then be consistent.

> The point being is that agitation and the particular style are not that important a factor.

That is only true if the developper does not produce reaction products which inhibit silver reduction by blocking crystallisation points. Phenidone and its siblings are known for that. Agitation removes these substances from the film surface.

piu58 said:

> That is only true if the developper does not produce reaction products which inhibit silver reduction by blocking crystallisation points. Phenidone and its siblings are known for that. Agitation removes these substances from the film surface.

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Changes to the fast reaction (that is development) have no effect, the overall development rate is determined by the diffusion rate! How many times must this fact be repeated?

FOOD FIGHT!!!!!

pdeeh said:

If I tuck the tank under my armpit and shuffle round the kitchen to the rhythm of La Cucaracha, I get particularly brilliant mid-tones

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You really are evil. I hear Darth Vader breathing.